Process for preparing 2-halogenpyridinaldehydes

Prodn. of 2-halopyridinealdehyde of formula (I) comprises reacting a cyano-, aminocarbonyl- or hydroxyimino-substd. olefin of formula (II) with a Vilsmeier reagent (III). X = Cl or Br; Q = H, halo, 1-8C alkyl (opt. substd. by CN or 1-4C alkoxy), 3-10C cycloalkyl, 6-12C aralkyl, 6-12C aryl or Het; He...

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Bibliographic Details
Main Authors HEITZER, HELMUT, BECK, GUNTHER
Format Patent
LanguageEnglish
French
German
Published 17.06.1998
Edition6
Subjects
CHEMISTRY
HETEROCYCLIC COMPOUNDS
METALLURGY
ORGANIC CHEMISTRY
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Summary:Prodn. of 2-halopyridinealdehyde of formula (I) comprises reacting a cyano-, aminocarbonyl- or hydroxyimino-substd. olefin of formula (II) with a Vilsmeier reagent (III). X = Cl or Br; Q = H, halo, 1-8C alkyl (opt. substd. by CN or 1-4C alkoxy), 3-10C cycloalkyl, 6-12C aralkyl, 6-12C aryl or Het; Het = 5- to 7-membered heteroaryl (contg. 1-3 N, O and/or S atoms); One of R1, R2 = CHO and the other = CHO, CN, OH, halo, 1-8C alkyl (opt. substd. by halo, CN or 1-4C alkoxy), 3-10C cycloalkyl, COR, 6-12C aralkyl, 6-12C aryl, 6-12C aryloxy, Het or O-Het; R = halo, 1-4C alkoxy, phenoxy or NR'R''; R', R'' = 1-4C alkyl; or R'+R'' = 4-6C alkylene opt. interrupted by O; Q' = Q, OH or 1-4C alkoxy; Y = CN, CONH2 or CH=NOH; One of R3, R4 = H and the other = R3, R4 = H, CN, halo, CONH2, 1-8C alkyl (opt. substd. by halo, CN, 1-4C alkoxy or OH), 1-8C alkoxy, 3-10C cycloalkyl, COR, COOH, 1-8C acyloxy, 6-12C aralkyl, 6-12C aryl, 6-12C aryloxy, Het or OHet. Cpds. (I) are new, except for 2-chloro-5-methyl-pyridine-3-carboxaldehyde; 2,3-dichloro-pyridine-5-carboxaldehyde; and 2-chloro-pyridine-3,5-dicarboxaldehyde. (III) is e.g. the prod. of an N-formylamide and an acid halide.
Bibliography:Application Number: EP19950112442